Re: Loading multiboot failed

[Andrei Borzenkov]

On 25.01.2024 18:57, Markbiophysicist wrote:
> Hello,
>
> Already from the Kali installer itself I have had problems with dual boot.
> The problem is that the other previously installed operating system does
> not recognize me. (Windows 10).

Do you mean that Windows is not offered in GRUB menu? Because Windows 
most certainly is not expected to recognize Linux.

> I have modified the /etc/default/grub file to enable the following
> configuration key:
> GRUB_DISABLE_OS_PROBER="false"
>
> I have done some testing by modifying the /etc/grub.d/40-custom file and
> adding custom entries and then running 'sudo update-grub' and testing the
> results. None have been successful.

"It does not work" is not very useful. Explain what you did, what were 
the results (what was on the screen, what errors, what happened etc).

> The last attempt gave me the following error:
> invalid signature

Well, EFI binary does not have standard boot sector signature expected 
by legacy BIOS GRUB.

> Please, I would appreciate it if you could tell me if there is any way to
> solve it or if there is a configuration error.
>
> The output of the bootinfo analysis script is as follows:
>
>                   Boot Info Script 0.78      [09 October 2019]
>
>
> ============================= Boot Info Summary:
> ===============================
>
>   => No boot loader is installed in the MBR of /dev/sda.
>   => Grub2 (v2.00) is installed in the MBR of /dev/sdb and looks at sector
>      3051722792 of the same hard drive for core.img. core.img is at this
>      location and looks for (,gpt3)/boot/grub. It also embeds following
>      components:
>
>      modules
>
> ---------------------------------------------------------------------------
>      fshelp ext2 part_gpt biosdisk
>
> ---------------------------------------------------------------------------
>
> sda1:
> __________________________________________________________________________
>
>      File system:       vfat
>      Boot sector type:  Windows 8/2012: FAT32
>      Boot sector info:  No errors found in the Boot Parameter Block.
>      Operating System:
>      Boot files:        /efi/Boot/bootx64.efi /efi/kali/grubx64.efi
>                         /efi/Microsoft/Boot/bootmgfw.efi
>                         /efi/Microsoft/Boot/bootmgr.efi
>                         /efi/Microsoft/Boot/memtest.efi
>
> sda2:
> __________________________________________________________________________
>
>      File system:
>      Boot sector type:  -
>      Boot sector info:
>
> sda3:
> __________________________________________________________________________
>
>      File system:       ntfs
>      Boot sector type:  Windows 8/2012: NTFS
>      Boot sector info:  No errors found in the Boot Parameter Block.
>      Operating System:
>      Boot files:        /Windows/System32/winload.exe
>
> sda4:
> __________________________________________________________________________
>
>      File system:       ntfs
>      Boot sector type:  Windows 8/2012: NTFS
>      Boot sector info:  No errors found in the Boot Parameter Block.
>      Operating System:
>      Boot files:
>
> sdb1:
> __________________________________________________________________________
>
>      File system:       ntfs
>      Boot sector type:  Windows 8/2012: NTFS
>      Boot sector info:  No errors found in the Boot Parameter Block.
>      Operating System:
>      Boot files:
>
> sdb2:
> __________________________________________________________________________
>
>      File system:       swap
>      Boot sector type:  -
>      Boot sector info:
>
> sdb3:
> __________________________________________________________________________
>
>      File system:       ext4
>      Boot sector type:  -
>      Boot sector info:
>      Operating System:  Kali GNU/Linux Rolling
>      Boot files:        /boot/grub/grub.cfg /etc/fstab
>                         /boot/grub/i386-pc/core.img
>
> sdb4:
> __________________________________________________________________________
>
>      File system:       ntfs
>      Boot sector type:  Unknown
>      Boot sector info:  No errors found in the Boot Parameter Block.
>      Operating System:
>      Boot files:

Apparently Windows is installed for UEFI boot and Linux is installed for 
legacy boot. os-prober will only check for the matching Windows 
installation - if Linux is booted in legacy mode, it will not look for 
Windows in UEFI mode.
...

> menuentry "Windows 10" {
> set root='(hd1,1)'
> insmod part_gpt
> insmod fat
> insmod chain
> chainloader /EFI/Microsoft/Boot/bootmgr.efi
> }

You cannot chainload EFI binary when booted in legacy BIOS mode.